It's amazing how fragile the atmosphere looks from space, said American astronaut Mary Cleave. All we have is a thin film of air to protect us.

'When you look at your planet from space, it's beautiful, fragile, and there's this little thin layer all the way around: our atmosphere. And that's the only thing that protects us from the really bad vacuum in outer space. This little fragile layer, the atmosphere, is part of our life support system. We need to be really careful with it.' -- Mary Cleave

'Our atmosphere connects us all. What happens in Africa affects North America. What happens in North America affects Asia.' -- Dan Barry, American astronaut

Views from space show the destruction humans have caused since the dawn of the industrial age.

'Less than 550 humans have orbited the Earth. Those of us lucky enough to have done so more than once have not only heard about the negative impact that the industrial age has had on our planet, we've seen it with our own eyes.' -- Michael López-Alegría, American astronaut

'The view from space is just breathtaking. And at the same time we recognise deforestation and wildfires, and so on, which are related to climate change.' -- Naoko Yamazaki, Japanese astronaut

It's also easy to see lakes dry up and pollution spread.

The Aral Sea has shrunk significantly. The left image shows the lake in 1977, the middle in 1998 and the right in 2010.

'We astronauts have been witnessing the continued shrinking of the Aral Sea, the burning rain forests along the Amazon and in Indonesia, the polluted air over industrial zones, and the dirty water at the river deltas.' -- Ernst Messerschmid, German astronaut

We're the only caretakers of Earth, the astronauts say, so it's our job to watch over of the planet.

'We are citizens of space, and stewards of Earth. We need to take actions to build (a) global climate alliance in order to protect our environment.' -- Soichi Noguchi, Japanese astronaut

Dutch astronaut Wubbo Ockels suggested that the Earth has cancer, just like him, in a heartbreaking message.

YouTube/Planetary Collective

'Suppose I can transfer the experience which I have to you. Then you would go out and see the Earth. And when you have let's say the spirit and the insight and the attitude of an astronaut, you start to love the Earth. And if you really love something, you don't want to lose it. Our Earth has cancer. I have cancer, too.' -- Wubbo Ockels